1338
111E O it A AND PRACTICE OF ENGINEERING.
Book II.
Fig.2151.
Fig. 2150.
planks must cover thetwo lines of the curveor mould, that thetrue sweep may beobtained throughout.
Philibert Delorme fixes the length ofthese planks for everykind of curve at notmore than 4 feet, butthis rule may be oc-casionally departedfrom, when we haveto follow a curvewhich is irregular;it is perhaps better totake such lengths asshall enable us todivide the curve intoan equal number ofparts, the length ofwhich may vary ineach division. Whenthese lengths are de-termined upon, drawlines perpendicular tothe curves, which willindicate the directionto be given to thejoints of the boards;after these are cutand adjusted, a se-cond row is so dis-posed that its jointswill fall over themiddle of the planks